1. Field of the Invention
The present invention relates to a semiconductor integrated circuit device. More specifically, the invention relates to a system large-scale integrated circuit (LSI) including a storage unit that stores information such as replacement information of memory circuits integrated on a chip, chip identification codes and setting information for setting circuit constants of, e.g., power supply circuits, and the like.
2. Description of the Related Art
With the recent advance of integrated circuit technology, a semiconductor integrated circuit device called a system LSI including various types of circuits having different functions and integrated on one or more chips has been achieved. As circuits integrated on the system LSI, there are a logic circuit for performing various operations, a memory circuit for storing information such as results of the operations, a power supply circuit such as an internal potential generation circuit for generating an internal potential, different types of analog circuits, and the like.
Some of the above circuits need their internal settings to be changed after the system LSI is manufactured and tested or after it is sealed in a package. As settings to be changed, there can be considered replacement information for replacing a defective cell with a defect-free cell in the memory circuit and setting information for setting circuit characteristics (circuit constant) of the circuit in the internal potential generation circuit. Conventionally, such information is stored in a nonvolatile memory on a chip or outside a chip. For simplification of management of a system LSI sealed in a package, each chip has coded identification information (chip identification code) and, in such a case, too, the nonvolatile memory is used.
In the system LSI so configured, information items are read in sequence from the nonvolatile memory at power-on. The read information items are transferred to a register for storing chip identification codes, a register for storing setting information of the internal potential generation circuit, and a register for storing replacement information of the memory circuit. Thus, the internal settings of the respective circuits are performed in accordance with the information items stored in the registers.
As the above nonvolatile memory, a fuse macro including a plurality of fuse elements has, conventionally, often been used. Well-known examples of the above-described fuse elements include fuses for fusing a wiring layer by a laser beam, fuses for fusing a wiring layer by current (current-fusing type), and fuses for breaking a gate oxide film of a transistor by a high voltage (high-voltage breaking type). These can be added with the manufacturing process of a system LSI being hardly changed, and the occupied areas are small and the control thereof is easy, which leads to a broad range of use thereof. Further, because such fuse elements can be programmed only once from the property thereof, they are called one-time programmable (OTP) memories. Note that, with respect to some of the fuse elements which are electrically programmed, such as a current-fusing type and a high-voltage breaking type, there is the advantage that programming can be carried out even after the system LSI is sealed in a package, which has been attracting attention in particular.
However, there is a problem in that no information can be overwritten (rewritten) to a blown fuse element. If a fuse element is blown only once, the fuse macro can serve as a nonvolatile storage unit sufficiently. However, various types of tests are conducted on a system LSI and there is a case where the written information has to be rewritten after another test. The fuse macro cannot cope with this case.
As the prior art of the present invention, for example, U.S. Pat. No. 6,102,963 proposes transferring data serially from a data-rewritable nonvolatile memory to a volatile programmable logic device (PLD).